The Aviator star Kelli Garner stars as Marilyn Monroe in the four-hour event that covers Marilyn's life from a lonely young woman struggling with a lonely, loveless existence in the absence of her mother Gladys (played by Susan Sarandon) to blossoming into a funny, smart, ambitious woman who turned herself into the symbol of an era.

One of the biggest secrets revealed is that Marilyn's mother was institutionalized for mental illness.

"I think you'll be surprised to learn about the mental disease that ran in her family," Kelli said. "I had no idea that her mother was in and out of institutions -- diagnosed schizophrenic."

Marilyn was sent to a series of orphanages and foster homes when her mother was institutionalized, as she grew up without a father. The movie studio told the world that Marilyn's mother was dead, and when the two later became close, they had to keep their relationship hidden.

Unfortunately, Marilyn went on to inherit her mother's mental illness, as her obsession with President John F. Kennedy drove her over into an insane asylum.

"She went from nothing to being on the top of the biggest mountain to just tragically tumbling right off of it," Kelli said.